Laser Cutting Strengthened Glass

ABSTRACT

Methods for cutting strengthened glass are disclosed. The methods can include using a laser. The strengthened glass can include chemically strengthened, heat strengthened, and heat tempered glass. Strengthened glass with edges showing indicia of a laser cutting process are also disclosed. The strengthened glass can include an electrochromic film.

FIELD OF THE DISCLOSURE

The present disclosure and inventions relate generally to methods forcutting strengthened glass, such as thermally strengthened glass, tomethods for fabricating electrochromic composites, to methods forfabricating electrochromic devices, and to methods for fabricatinginsulated glass units. The disclosure and inventions also relate to cutthermally strengthened glass, to electrochromic composites, toelectrochromic devices and to insulated glass units.

BACKGROUND

Strengthened glass can be used in a variety of applications that requirehigher strength than annealed glass. Examples of strengthened glassinclude chemically-strengthened and thermally-strengthened glass.Thermally-strengthened glass includes both heat-strengthened glass andfully-tempered glass. Chemically-strengthened glass andthermally-strengthened glass both have strained surface regions undercompressive stress and an inner region under tensile stress.Chemically-strengthened glass can be manufactured by submerginguntreated glass in a molten potassium salt bath. Typical temperaturesare 450° C. to 550° C. and a prototypical salt is KNO₃. The sodium ionsin the glass surface are exchanged with the potassium ions from thebath. This time dependent ion exchange process results in the formationof compressed surface regions on the glass. Thermally-strengthened glassis typically manufactured by heating annealed glass in a furnace totemperatures over 600° C. followed by rapidly cooling the glass. Suchthermal treatment induces residual compressive stress at the surfaces ofthe glass and tensile stress in the center of the glass.

It is generally accepted in the art that thermally-strengthened glasscannot be cut after strengthening. For example, ASTM C1048-04 section7.9 states, “Heat-treated flat glass cannot be cut after tempering.Fabrication altering the stress distribution, surface or edge shape, ordimensions must be performed before being heat treated.”

As such, conventional methods for applications that require custom sizesfor strengthened glass, especially thermally strengthened glass,typically cut the glass to the desired size prior to the strengtheningprocess. After cutting, the custom sized glass substrates arestrengthened. Processes for producing strengthened glass parts andproducts are mature, widespread, and able to meet the needs of many flatglass processors.

Processing many different sizes of glass sheet is less desirable forcertain commercial applications, however, because machinery andapplications may need to be customized for different sizes of glasssheet. Processing different sizes of glass sheets also decreases theefficiency and throughput for such commercial processes. Processingmultiple sizes of glass sheets or substrates can be especiallychallenging for processes which include depositing coatings on the glasssubstrates such as vacuum sputtering, dip coating, or slot die coating.Additionally, processing glass prior to strengthening increases thechances of the glass breaking during earlier processing steps.

Despite such shortcomings, however, the art has not heretofore developedcommercially meaningful glass fabrication approaches which would allowpreparing and processing thermally strengthened glass in standardized,large-scale format with subsequent cutting to custom sizes forparticular applications. In addition to the common industryunderstanding that cutting processes do not work for thermallystrengthened glass, some industrial applications have additionaltechnical challenges which make such an approach less certain. Forexample, coating glass substrates with thin films prior to strengtheningmay be undesirable for applications that include films that may bealtered by process conditions associated with strengthening (e.g., wherefilms may not withstand the temperatures used for thermal strengtheningthe glass).

Methods for cutting chemically-strengthened are known but typically haveresulted in cut glass substrates with unacceptable edge defects. Theseedge defects are unacceptable for many applications because they greatlyreduce the overall strength of the cut glass and can serve as nucleationpoints for larger cracks. Mechanical steps for processing the edges havebeen used (e.g., grinding the edges). These mechanical steps produceparticles that are unacceptable for many applications. Notably, forexample, the generated particles can cause damage to the surface of theglass and coatings formed on the surface of the glass.

U.S. Patent Publication No. 2011/0304899 to Kwak et al. (“Kwak et al.”)acknowledges that tempered glass cannot be cut and that electrochromicdevices cannot withstand the process conditions required to temper theglass. Kwak et al. address this problem by forming the electrochromicdevice on a piece of annealed glass followed by laminating the annealedglass to a piece of strengthened glass. However, the resultant devicedoes not meet the strength requirements for many applications unless avery low thermal expansion glass such as borosilicate glass is used, andborosilicate glass is very expensive relative to other types of glasssuch as soda-lime glass.

Similarly, U.S. Patent Publication No. 2012/0182593 to Collins et al.discloses strengthening the glass substrate after cutting by laminatingto a strengthened piece of glass. This suffers from the same limitationsas Kwak et al.

Many different methods for cutting or scribing glass by using laserenergy have been previously reported. A common approach is to applylaser energy to a piece of glass under conditions effective to ablatethe glass along a desired cutting line. Ablation occurs when the energybeing delivered to the glass is sufficient to vaporize the glass. Thismethod typically produces undesirable cracks and debris, and because ofthe relatively wide heat affected area, the kerf width is notnegligible. These drawbacks have prevented the successful application ofthis type of method to cutting strengthened glass.

U.S. Pat. No. 5,609,284 to Kondratenko and U.S. Pat. No. 6,787,732 toXuan report kerf-free methods of cutting glass by thermal stress inducedscribing. These methods have fewer drawbacks than the ablative methodsbut required the propagation of a crack along the cut line as well as amethod to initiate the crack propagation. Relying on the propagation ofa crack along a defect line is not preferred for cutting strengthenedglass and especially for thermally strengthened glass, because cracksmay propagate uncontrollably or simply reduce the strength of the cutedge making the cut piece of glass unusable.

U.S. Pat. No. 8,327,666 to Harvey et al. (“Harvey et al.”) disclosesusing a nanosecond laser to cut chemically-strengthened glass in whichthe nanosecond laser is focused within the thickness of the glass inorder to create a line of local defects which is referred to as the“laser induced damage line”. This damage line allows the chemicallystrengthened glass to be cleaved by propagating a crack along this line.However, cutting thermally-strengthened glass is different from andsignificantly more difficult than cutting chemically strengthened glass(e.g., due to different compressive and tensile stress properties) andno details on the laser process conditions, evidence, or examples ofcutting thermally-strengthened glass are provided. Harvey et al.discloses an example of cutting chemically strengthened glass with a 50lam thick compression layer using a 355-nm nanosecond Nd-YAG laser. Noenabling description or examples are provided for cuttingthermally-strengthened glass or for cutting strengthened glass thickerthan 2.0 mm. In fact, the disclosed approach would not be successfullyapplied to thermally-strengthened glass because the tensile stress inthe center region of thermally-strengthened glass is much higher anddefects or laser induced damage in this region could cause the glass toexplode into small fragments. In addition, the propagation of a crackthrough thermally-strengthened glass would be much harder to control asthe mean free path of crack propagation is much smaller than inchemically strengthened glass and the total stored energy is muchgreater. Finally, even if the laser induced damage line methodoccasionally yields successfully cut thermally-strengthened glass, theedges created by the crack propagation would be overpopulated with manymicro cracks that would greatly reduce the strength of the cut glass andprevent it from passing standard ASTM strength tests required forbuilding and transportation applications.

Generally, part of the laser energy applied to the glass is converted toheat. The amount of glass subject to the laser heat is typically calledthe heat affected zone. For laser ablation techniques, using a CO₂ laserfor example, the heat affected zone is quite large and would not beuseful for cutting strengthened glass as the strain created by the heatwould cause the glass to break. Other techniques for cutting glassconsist of creating a defect line or damage line along which the glasscan be cleaved. As noted above, Harvey et al. disclose creating a “laserinduced damage line” within the thickness of the glass. In order to dothis, the laser is focused in the region of the glass under tensilestress and the energy provided by the laser is converted to thermalenergy and locally modifies the glass thus creating a defect. Most ofthe examples provided by Harvey et al. are for glass compositions havinga low coefficient of thermal expansion (CTE). Higher CTE glass would beexpected to be much more difficult to cut using this method because thestrain induced by the local heating could be enough to initiate thepropagation of a crack in the tensile region of the glass, where Harveyet al. claims should be the location of the laser induced damage line.In contrast, the methods disclosed herein do not create a damage line inthe center tensile region and generally avoid focusing the laser in theregion of high tensile stress. It is desirable to avoid or minimizeforming a damage line in the center tensile region ofthermally-strengthened glass. The methods disclosed herein can addressthese problems.

Methods for cutting thermally-strengthened glass wherein at least someof the cut pieces of glass have good edge quality and high strength aredesired. Methods for cutting chemically-strengthened glass with improvededge qualities wherein at least some of the cut pieces of glass havegood edge quality and high strength are also desired. Methods forcutting composites or devices comprising a strengthened glass substrate(e.g., thermally-strengthened or chemically-strengthened glasssubstrate) wherein at least some of the cut pieces of composites ordevices have good edge quality and high strength are also desired.

SUMMARY OF THE DISCLOSURE

Generally, the inventions described herein include methods for cuttingstrengthened glass, such as thermally-strengthened glass. The inventionsalso include methods for fabrication of composites (e.g., electrochromiccomposites), devices (e.g., electrochromic devices) and insulated glassunits, in each case comprising strengthened glass, where suchfabrication approaches include cutting a strengthened glass substrate(e.g., a thermally- or chemically-strengthened glass substrate). Furtherinventions are directed to a piece of cut strengthened glass, such as apiece of cut thermally strengthened glass. The inventions are alsodirected to composites (e.g., electrochromic composites), devices (e.g.,electrochromic devices) and insulated glass units, in each casecomprising strengthened glass.

In a first general aspect, inventions are directed to methods of cuttingstrengthened glass.

In a first approach of the first aspect, inventions are directed tomethods of cutting thermally strengthened glass. Such methods includeproviding a thermally-strengthened glass substrate and applying laserenergy to the thermally-strengthened glass substrate under conditionseffective to cut the thermally-strengthened glass substrate. Applyinglaser energy to the thermally strengthened glass substrate can includeforming a filamentation pattern defined by a series of regularlyrecurring filamentation traces in the thermally strengthened glasssubstrate. The series of filamentation traces can be substantiallyparallel to each other. The series of filamentation traces can besubstantially perpendicular to a surface of the thermally strengthenedglass substrate. The thermally strengthened glass substrate, in eachcase, can be a heat-strengthened glass substrate or a thermally temperedglass substrate. The method can further comprise fabricating orassembling an electrochromic composite or an electrochromic device usingthe cut piece of thermally strengthened glass. The methods can alsoinclude fabricating or assembling an insulated glass unit using the cutpiece of thermally strengthened glass substrate.

In a second approach of the first aspect, inventions are directed tomethods of cutting a strengthened glass substrate, such as a thermallystrengthened glass substrate or a chemically strengthened glasssubstrate. Such methods include providing a strengthened glass substrateand applying laser energy to the strengthened glass substrate underconditions effective to cut the thermally-strengthened glass substrateby a protocol which includes forming a filamentation pattern defined bya series of regularly recurring filamentation traces in the strengthenedglass substrate. The series of filamentation traces can be substantiallyparallel to each other. The series of filamentation traces can besubstantially perpendicular to a surface of the strengthened glasssubstrate. A thermally strengthened glass substrate, in each case, canbe a heat-strengthened glass substrate or a thermally tempered glasssubstrate. The method can further comprise fabricating or assembling anelectrochromic composite or an electrochromic device using the cut pieceof strengthened glass. The methods can also include fabricating orassembling an insulated glass unit using the cut piece of strengthenedglass substrate.

In a third approach of the first aspect, inventions are directed tomethods of cutting a strengthened glass substrate, such as a thermallystrengthened glass substrate or a chemically strengthened glasssubstrate. Such methods include providing a strengthened glasssubstrate, applying laser energy to the strengthened glass substrateunder conditions effective to cut the strengthened glass substrate, andtreating the cut edges to increase the strength of the glass substrate.Treating the cut edges can comprise applying laser energy to cut theedge at an obtuse angle relative to a surface of the strengthened glasssubstrate to form a chamfered edge. Treating the cut edges can comprisea chemical treatment. Treating the cut edges can comprise applying acoating to the cut edge. A coating on the cut edge can comprise a metal,an oxide, or a polymer. Applying laser energy to the strengthened glasssubstrate can include forming a filamentation pattern defined by aseries of regularly recurring filamentation traces in the strengthenedglass substrate. The series of filamentation traces can be substantiallyparallel to each other. The series of filamentation traces can besubstantially perpendicular to a surface of the strengthened glasssubstrate. A thermally strengthened glass substrate, in each case, canbe a heat-strengthened glass substrate or a thermally tempered glasssubstrate. The method can further comprise fabricating or assembling anelectrochromic composite or an electrochromic device using the cut pieceof strengthened glass. The methods can also include fabricating orassembling an insulated glass unit using the cut piece of strengthenedglass substrate.

In the methods of the first general aspect, including the methods of anyof the first, second or third approaches thereof, conditions effectiveto cut the strengthened glass substrate can include:

(a) focusing laser energy at a first position on or in proximity of afirst surface of the strengthened glass substrate,

(b) pulsing the focused laser energy for a pulse duration ranging fromabout 10 femtoseconds to about 100 picoseconds at a pulse frequencyranging from about 100 kHz to about 100 MHz, the pulsed laser having apulse energy of about 1 micro Joule (μJ) to about 100 μJ, and having awavelength of about 250 nm to about 1100 nm,

(c) translating the focal point of the pulsed focused laser energyrelative to the first surface,

(d) repeating steps (b) and (c) to form a filamentation pattern definedby a series of regularly recurring substantially parallel filamentationtraces, and

(e) separating the strengthened glass substrate along the filamentationpattern to form two or more cut pieces of the strengthened glasssubstrate.

In a second general aspect, the inventions are directed to methods forfabricating two or more electrochromic composites. The methods includeproviding an electrochromic composite comprising a strengthened glasssubstrate having a first surface and an opposing second surface, anelectrically conductive layer supported on the first surface of thestrengthened glass substrate, and an electrochromic layer in electroniccommunication with the electrically conductive layer; and applying laserenergy to the strengthened glass substrate under conditions effective tocut the strengthened glass substrate to form two or more electrochromiccomposites. The electrically conductive layer can include a metal or ametal oxide. The electrically conductive layer can include a transparentconductive material. The electrochromic layer can be an anodicelectrochromic layer. The electrochromic layer can be a cathodicelectrochromic layer. The electrochromic composite can be provided as amother glass composite. The electrochromic composite can be provided asa mother glass composite comprising an array of two or more spatiallydiscrete electrochromic composites, each comprising a correspondingspatially discrete portion of the strengthened glass substrate. Laserenergy can be applied to the strengthened glass substrate to cut themother glass composite and separate two or more spatially discreteelectrochromic composites. In preferred approaches of the second generalaspect of the invention, the strengthened glass substrate can be cutaccording to the methods of the first general aspect of the invention,including any of the first, second or third approaches thereof, asdescribed generally above, and more specifically hereafter. The methodcan further comprise fabricating or assembling an electrochromic deviceusing one or more of the formed electrochromic composites. The methodscan also include fabricating or assembling an insulated glass unit usingone or more of the formed electrochromic composites.

In a third general aspect, the inventions are directed to methods forfabricating two or more electrochromic devices. The methods includeproviding an electrochromic device comprising a strengthened glasssubstrate and applying laser energy to the strengthened glass substrateunder conditions effective to cut the strengthened glass substrate toform two or more electrochromic devices. The electrochromic device caninclude two electrically conductive layers and an electrochromic cell inelectronic communication with the electrically conductive layers, wherethe electrically conductive layers and electrochromic cell aresupported, directly or indirectly, on a surface of the strengthenedglass substrate. The electrochromic cell can include an anode, acathode, and an ion conductor in electronic communication with the anodeand cathode with at least one of the anode or cathode comprising anelectrochromic material. The electrochromic device can be provided as amother glass composite. The mother glass composite can comprise an arrayof two or more spatially discrete electrochromic devices, eachcomprising a corresponding spatially discrete portion of thestrengthened glass substrate. Laser energy can be applied to thestrengthened glass substrate to cut the mother glass composite andseparate two or more spatially discrete electrochromic composites. Inpreferred approaches of the third general aspect of the invention, thestrengthened glass substrate can be cut according to the methods of thefirst general aspect of the invention, including any of the first,second or third approaches thereof, as described generally above, andmore specifically hereafter. The methods can also include fabricating orassembling an insulated glass unit using one or more of the formedelectrochromic devices.

In a fourth general aspect, the inventions are directed to methods forfabricating an insulated glass unit. The methods include providing afirst mother glass comprising a first strengthened glass substrate;applying laser energy to the first strengthened glass substrate underconditions effective to cut the strengthened glass substrate to form afirst glass lite; providing a second glass lite; and assembling thefirst glass lite and the second glass lite into an insulated glass unit.The methods can include providing a second mother glass comprising asecond strengthened glass substrate and cutting the second strengthenedglass substrate to form the second glass lite. The first and/or secondstrengthened glass substrate can be independently selected fromthermally-strengthened glass substrates or chemically strengthened glasssubstrates. The first and second strengthened glass substrates can beprovided as a component of an electrochromic composite, or as acomponent of an electrochromic device. The mother glass composite cancomprise an array of two or more spatially discrete electrochromiccomposites or spatially discrete electrochromic devices, each comprisinga corresponding spatially discrete portion of the strengthened glasssubstrate. Laser energy can be applied to the strengthened glasssubstrate to cut the mother glass composite and separate two or morespatially discrete electrochromic composites or electrochromic devices.In preferred approaches of the fourth general aspect of the invention,the strengthened glass substrate can be cut according to the methods ofthe first general aspect of the invention, including any of the first,second or third approaches thereof, as described generally above, andmore specifically hereafter.

In a fifth general aspect, the inventions are directed to a piece of cutstrengthened glass.

In a first approach of the fifth general aspect, the inventions aredirected to a piece of cut thermally-strengthened glass. The piece ofcut glass includes a thermally-strengthened glass substrate having afirst surface, an opposing second surface, and a peripheral edge betweenthe first surface and the second surface with the edge having indicia ofa laser filamentation cutting process. The thermally strengthened glasssubstrate can include a heat treated glass substrate or athermally-tempered glass substrate. The strengthened glass substrate canbe soda-lime glass.

In a second approach of the fifth general aspect, the inventions aredirected to a piece of cut strengthened glass which comprises astrengthened glass substrate having a first surface, an opposing secondsurface, and a peripheral edge between the first surface and the secondsurface with the peripheral edge having indicia of a laser filamentationcutting process, and a treated edge surface. The treated edge surfacecan be a chamfered edge surface. The treated edge surface can be achamfered edge at an obtuse angle relative to a surface of thestrengthened glass substrate. The treated edge surface can include asurface having a low surface roughness. The treated edge surface cancomprise a coating over the cut edge. A coating on the cut edge cancomprise a metal, an oxide, or a polymer. The strengthened glasssubstrate can include a thermally strengthened glass substrate or achemically strengthened glass substrate. The strengthened glasssubstrate can be soda-lime glass.

For the piece of cut strengthened glass of the fifth general aspect,including the cut glass piece of any of the first or second approachesthereof, indicia of the laser filamentation cutting process can includea filamentation pattern defined by a series of regularly recurringfilamentation traces. The series of filamentation traces can besubstantially parallel to each other. The series of filamentation tracescan be substantially perpendicular to a surface of the strengthenedglass substrate. The series of filamentation traces can define aplurality of the filamentation traces having a width ranging from about0.5 microns (μm) to about 10 μm. The adjacent filamentation traces canbe separated by an average distance ranging from about 1 μm to about 30μm.

In a sixth general aspect, the inventions are directed to anelectrochromic composite. Such electrochromic composites includes astrengthened glass substrate having a first surface, an opposing secondsurface, and a peripheral edge between the first surface and secondsurface, the edge having indicia of a laser filamentation cuttingprocess; an electrically conductive layer supported on the first surfaceof the strengthened glass substrate; and an electrochromic layer inelectronic communication with the electrically conductive layer. Thestrengthened glass substrate can include a chemically-strengthened glassor thermally-strengthened glass. The strengthened glass substrate can besoda-lime glass. The indicia of the laser filamentation cutting processcan include a filamentation pattern defined by a series of regularlyrecurring filamentation traces. The series of filamentation traces canbe substantially parallel to each other. The series of regularlyrecurring filamentation traces can be oriented substantiallyperpendicular to the first and second surfaces of the strengthened glasssubstrate. A plurality of the filamentation traces can have a widthranging from about 0.5 μm to about 10 μm. The adjacent filamentationtraces can be separated by an average distance ranging from about 1 μmto about 30 μm.

In a seventh general aspect, the inventions are directed toelectrochromic devices. The electrochromic devices include at least onestrengthened glass substrate having a first surface, an opposing secondsurface and a peripheral edge between the first surface and secondsurface, the peripheral edge having indicia of a laser filamentationcutting process. The electrochromic device can include two electricallyconductive layers and an electrochromic cell in electronic communicationwith the electrically conductive layers, the electrically conductivelayers and electrochromic cell being supported, directly or indirectly,on the first surface or second surface of the strengthened glasssubstrate. The electrochromic devices can also include: a first glasssubstrate having a first surface and an opposing second surface, a firstelectrically conductive layer supported on the first surface of thefirst glass substrate, and an electrochromic anodic layer in electroniccommunication with the first electrically conductive layer. Theelectrochromic devices can include a second glass substrate having afirst surface and an opposing second surface, a second electricallyconductive layer supported on the second surface of the second glasssubstrate, and an electrochromic cathodic layer in electroniccommunication with the second electrically conductive layer. Theelectrochromic devices can include an ion-conducting material inelectronic communication with each of the electrochromic anodic layerand the electrochromic cathodic layer. The indicia of the laserfilamentation cutting process can include a filamentation patterndefined by a series of regularly recurring filamentation traces. Theseries of filamentation traces can be substantially parallel to eachother. The series of regularly recurring filamentation traces can beoriented substantially perpendicular to the first and second surfaces ofthe strengthened glass substrate. A plurality of the filamentationtraces can have a width ranging from about 0.5 μm to about 10 μm. Theadjacent filamentation traces can be separated by an average distanceranging from about 1 μm to about 30 μm.

In an eighth general aspect, the inventions are directed to insulatedglass units. The insulated glass units include a first lite comprising astrengthened glass substrate having a first surface, an opposing secondsurface and a first peripheral edge between the first surface and secondsurface. The insulated glass units also include a second lite comprisinga glass substrate having a first surface, an opposing second surface,and a second peripheral edge between the first surface and secondsurface and a spacer element providing spatial separation between thefirst glass lite and the second glass lite. At least one of firstperipheral edge or the second peripheral edge has indicia of a laserfilamentation cutting process. The second lite can be a strengthenedglass substrate. The strengthened glass substrates can bechemically-strengthened or thermally-strengthened. The strengthenedglass substrate can be soda-lime glass. The indicia of the laserfilamentation cutting process can include a filamentation patterndefined by a series of regularly recurring filamentation traces. Theseries of filamentation traces can be substantially parallel to eachother. The series of regularly recurring filamentation traces can beoriented substantially perpendicular to the first and second surfaces ofthe strengthened glass substrate. A plurality of the filamentationtraces can have a width ranging from about 0.5 μm to about 10 μm. Theadjacent filamentation traces can be separated by an average distanceranging from about 1 μm to about 30 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features and advantages of the presentdisclosure will be obtained by reference to the following detaileddescription that sets forth illustrative embodiments, in which theprinciples of the disclosure are utilized, and the accompanyingdrawings.

FIG. 1A illustrates an example of an electrochromic composite.

FIG. 1B illustrates an example of an electrochromic device.

FIG. 2A illustrates an example of a strain profile forchemically-strengthened glass and a thermally-strengthened glass.

FIG. 2B illustrates an example of a strain profile for aheat-strengthened glass.

FIG. 3 illustrates an example of a strain profile for a thinchemically-strengthened glass and a thicker thermally strengthened glassalong with break patterns for each glass.

FIG. 4 illustrates a schematic of laser focus positions in accordancewith some embodiments.

FIG. 5 illustrates a schematic of laser energy applied to a piece ofglass in accordance with some embodiments.

FIG. 6A is a schematic illustration of a method for cutting a glasssubstrate in accordance with an embodiment.

FIG. 6B is a schematic illustration of a method for cutting laminatesassembled from glass substrates in accordance with an embodiment.

FIGS. 7-7C are schematic illustrations of laser edge treatments inaccordance with embodiments.

FIGS. 8-8A are schematic illustrations of polymeric edge treatments ofglass substrates in accordance with embodiments.

FIGS. 9-9A are schematic illustrations of chemical edge treatments ofglass substrates in accordance with embodiments.

FIG. 10 is an illustration of various modifications to an edge.

FIG. 11 is a micrograph of a mechanically ground edge.

FIG. 12 is a schematic illustration of chemically strengthening a stackof laser cut glass in accordance with an embodiment.

FIG. 13A is a schematic illustration of a glass substrate, not drawn toscale, showing indicia of a laser filamentation process.

FIGS. 13B and 14 are images of the edge of thermally-strengthened glasssubstrates cut using the methods described herein.

FIG. 15 is an image of a mechanically cleaved edge of a glass substrate.

FIG. 16 is an image of an edge of a thermally-strengthened glasssubstrate cut using the methods described herein.

FIG. 17 is an image of an edge of a fully tempered glass substrate cutusing the methods described herein at a magnification of 50×.

FIG. 18 is an image of an edge of a thermally-strengthened glasssubstrate cut using the methods described herein.

FIG. 19 is an image of an edge of a thermally-strengthened glasssubstrate cut using the methods described herein.

FIG. 20 is a graph of the modulus of rupture distribution fit by aWeibull distribution of the results of the tests described in Example 5.

FIG. 21 is a graph of the modulus of rupture distribution fit by aWeibull distribution of the results of the tests described in Example 6.

FIG. 22 is a table illustrating the strengths of laser cut annealed SLGand mechanically cut annealed glass.

DETAILED DESCRIPTION

The inventions described herein enable cutting of thermally-strengthenedglass and, independently, the fabrication of composites (e.g.,electrochromic composites), devices (e.g., electrochromic devices) andinsulated glass units comprising strengthened glass, where suchfabrication approaches include cutting a strengthened glass substrate(e.g., a thermally- or chemically-strengthened glass substrate).Accordingly, methods for cutting strengthened glass using a laser aredisclosed herein. Preferably, a laser filamentation process can be usedto cut a strengthened glass substrate. Cut strengthened glass, andcomposites and devices comprising cut strengthened glass, are alsodisclosed herein, each including strengthened glass having a cut edgewith indicia from the laser cutting processes disclosed herein. Examplesof strengthened glass include chemically-strengthened glass andthermally-strengthened glass. A composite or device can include layers,films, or coatings, in each case formed on or supported by (in eachcase, directly or indirectly) the strengthened glass. The materialformed on the strengthened glass substrate (e.g., as a layer, film orcoating) can include materials that are sensitive to glass strengtheningprocesses. In preferred embodiments, the material formed on thestrengthened glass substrate can include an electrochromic material.

The strengthened glass can support an electrochromic material.Electrochromic materials are materials that have a transmittance over adefined range of wavelengths that changes upon application of an appliedpotential. The optical or thermal properties of the electrochromicmaterial, including transmittance, can change with an applied voltage.The transmittance of electrochromic materials can change for variouswavelengths of light, such as infrared (IR) wavelengths, ultraviolet(UV) wavelengths, visible light, and combinations of these, uponapplication of an applied potential. With reference to FIG. 1A and FIG.1B, a strengthened glass substrate 100, 200 can be a component of adevice 20 or a composite 10, such as an electrochromic device or anelectrochromic composite, in each case comprising an electrochromicmaterial (e.g., depicted as an electrochromic layer 130, 230). Anelectrochromic device 20 can include an electrochromic cell. Anelectrochromic cell can be an electrochemical cell comprising a cathode,an ion conductor, and an anode, where at least one of the cathode oranode comprises an electrochromic material. Hence, an electrochromiccell is a type of electrochemical cell that has optical or thermalproperties that can change based on an applied voltage between the anodeand cathode. An electrochromic composite 10 can include one or morelayers formed on or supported by (each, directly or indirectly) astrengthened glass substrate 100, where at least one of the layerscomprises an electrochromic material (e.g., depicted as anelectrochromic layer 130). Hence, an electrochromic composite can be anelectrochromic half-cell—for example, comprising at least one of anelectrochromic anodic material, or alternatively an electrochromiccathodic material. An electrochromic film can be a component of anelectrochromic cell or half cell, such as an electrochromic device 20 oran electrochromic composite 10. Electrochromic composites andelectrochromic devices can also include one or more electricallyconductive layers 120, 220 supported on glass substrates 100, 200,respectively, and in electronic communication with electrochromic layers130, 230, respectively. In some embodiments the electrochromic materialcan be active for modulating visual wavelengths of light. In someembodiments the electrochromic material can be active for modulating IRwavelengths. In some embodiments the electrochromic material can beactive for modulating UV wavelengths.

Methods for cutting thermally-strengthened glass are disclosed herein.The thermally-strengthened glass substrate can support an electrochromicfilm, for example, as a component of an electrochromic device or anelectrochromic composite.

Methods for cutting thermally-strengthened glass with improved edgequality are disclosed herein. Methods disclosed previously for cuttingthermally-strengthened glass, consisting of propagating a crack along adamage line in the glass would result in poor edge quality and lowstrength.

Methods for cutting chemically-strengthened glass—for example, as acomponent of an electrochromic device or electrochromic composite aredisclosed herein. Methods which preferably provide a cut chemicallystrengthened glass with improved edge quality are disclosed herein.Conventional methods for cutting chemically strengthened glasssubstrates typically result in poor edge quality and cracks on the cutedges which reduce the strength of the cut piece of glass.

The methods disclosed herein can be used to cut strengthened glass byitself or strengthened glass having one or more layers or coatings (acomposite). In some embodiments such a composite is cut using themethods disclosed herein. The composite can be an electrochromiccomposite, and can, for example, include a partially-fabricatedelectrochromic device. In some embodiments an electrochromic devicecomprising a strengthened glass substrate can be cut using the methodsdisclosed herein. In some embodiments an integrated glass unitcomprising a strengthened glass can be assembled from the cutstrengthened glass substrate disclosed herein.

Benefits of the present inventions are particularly applicable forapplications that involve forming films, coatings, or layers onstrengthened glass substrates that are sensitive to high temperatures orthe chemical strengthening process. Benefits are also applicable forapplications involving composites or devices comprising glass substratesthat are sensitive to high temperatures or the chemical strengtheningprocess.

Conventional processes for coating and processing glass, such as sputtercoating, slot coating, dip coating, chemical vapor deposition atatmospheric pressure, roll coating, substrate transport, substrateregistration, and lamination can achieve higher utilizations and yieldswhen a single substrate size is used. It is thus advantageous tomanufacture coated glass components for automotive, residential andcommercial architectural glazing applications using one or a smallnumber of substrate sizes. The methods disclosed herein allow forprocessing larger substrate sizes with significantly increasedthroughput, which decreases manufacturing costs and allows for quickerturnaround for customer orders.

The methods and devices disclosed herein are applicable to manydifferent applications, generally including for example buildingapplications, automotive applications, and electronics applications. Themethods and devices are also applicable, more specifically, forelectrochromic devices such as active windows, polymer dispersed liquidcrystal devices, solar cells, building integrated photovoltaics, flatpanel displays, and suspended particle devices. Heat-strengthened glasscan be used in building applications. A variety of sizes and shapes ofglass are used in building applications. Custom sizes are often requiredfor glass used for building applications. Generally, buildingapplications require strengthened glass such as thermally strengthenedglass.

The ability to cut strengthened glass, such as thermally strengthenedglass, allows for processing steps to be performed on strengthened glassinstead of un-strengthened glass while maintaining a high throughput.The increased mechanical strength of the strengthened glass can reducethe chance of breakage or damage to the glass during subsequentprocessing, fabrication, or handling steps. The additional strength canalso enable processing and fabrication steps that were not acceptablefor un-strengthened glass substrates.

The methods disclosed herein can be used for any applications whereglass that is stronger than annealed glass is used. Strengthened glassincludes chemically-strengthened glass and thermally-strengthened glass.Thermally-strengthened glass includes heat-strengthened glass, temperedglass, and fully tempered glass. ASTM standards provide guidelines forthe physical properties of various types of strengthened glass.

Thermally-strengthened glass is typically manufactured by heatingannealed glass to temperatures higher than about 600° C. followed byrapidly cooling the glass surfaces. This thermal treatment induces astress profile in the glass with a region of compression at the surfacesand an area under tensile stress at the center of the glass, asillustrated in FIG. 2A (thermally tempered glass) and FIG. 2B(heat-strengthened glass). As illustrated in FIG. 2A, the transitionbetween the surface compression and center tension is more gradual inthermally-strengthened glass versus chemically-strengthened glass. Thesurface compression in thermally-strengthened glass is not limited byionic diffusion but rather thermal diffusion during the cooling step,and extends much deeper than the surface compression inchemically-strengthened glass. The compressed surface regions inthermally-strengthened glass typically each occupy about 20% of theglass thickness.

Thermally-strengthened glass includes heat-strengthened and fullytempered glass. According to ASTM C 1048-04, fully tempered glass isrequired to have a minimum surface compression of 69 MPa (10,000 psi) oran edge compression of not less than 67 MPa (9,700 psi). Fully temperedglass typically has a residual compressive surface stress of betweenabout 80 MPa and 150 MPa. Fully tempered glass typically has a surfacecompression layer of around 20% of the total glass thickness.

Heat-strengthened glass is produced using a similar process to fullytempered glass but with a slower cooling rate. ASTM C 1048-04 requiresthat heat-strengthened glass has a residual compressive surface stressbetween 24 MPa (3,500 psi) and 52 MPa (7,500 psi). Heat-strengthenedglass typically has a surface compression layer of around 20% of thetotal glass thickness as shown in FIG. 2B. For example the compressionlayers at the surface of heat-strengthened glass are about 640 μm for3.2 mm glass, about 440 μm for 2.2 mm glass, and about 320 μm for 1.6 mmglass. Heat-strengthened glass, as used herein, can also apply tothermally-strengthened glass having a residual compressive surfacestress between 24 MPa and 67 MPa.

Chemically-strengthened glass is typically manufactured by ion exchangein a molten salt bath. The ion diffusion is typically limited to theimmediate surface of the glass. The diffusion of larger ions into theglass surfaces causes compression in the surface regions of the glass.The depth of the compressively stressed layer in chemically strengthenedglass is a function of the amount of the temperature of the salt bath aswell as the amount of time the glass was immerged in the bath.Typically, the depth of layer is limited to around 20 μm to 200 μm. Asillustrated in FIG. 2A, the stress profile in chemically-strengthenedglass exhibits a sharp transition between the compressively stressedsurface and the center region under tensile stress.

For chemical strengthened glass, cutting and drilling of the glassremains possible but can adversely affect the edge strength and overallstrength of the glass. Chemically-strengthened glass is rarely used forarchitectural applications. In some cases chemically-strengthened glasscan be used for special geometries where usual tempering cannot be used.

FIG. 2A illustrates the cross-sectional stress profile of achemically-strengthened piece of glass and a thermally-strengthenedpiece of glass. The surface regions of compressive stress areresponsible for improved resistance against impact, bending, thermalshock, and scratches. The inner region of tensile stress, on the otherhand, is where cracks propagate and cause strengthened glass tofracture. It is significant that the tensile stress in the center regionis much greater in the thermally-strengthened glass than in thechemically-strengthened glass. Therefore, thermally-strengthened glassis more vulnerable to damage induced in the center tensile region thanchemically-strengthened glass. If the induced damage is significantenough, a crack will propagate rapidly through the glass. The crack canpropagate in random directions and at speeds of over 1000 m/s releasingpart of the stored elastic energy in creating fracture surfaces.Qualitatively, it is clear that there is significantly more storedenergy in thermally tempered glass than in chemically strengthened glassbecause the number of fragments, and hence fracture surfaces obtainedafter shattering, is much higher for thermally tempered glass. Thestored energy can be approximated theoretically by the followingequation: U=(6·V·σ²)/E, where V is the volume of the glass, σ is thecenter tension in the glass and E is Young's modulus for glass. Thisequation demonstrates the significance of the maximal tensile stress inthe center region. This equation also shows that increasing thethickness of the glass linearly increases the stored energy. Therefore,thermally-strengthened glass is much more difficult to successfully cutwithout shattering and much more difficult to successfully cut yieldinga piece that is high strength, as compared to chemically strengthenedglass.

The different break patterns between chemically-strengthened andthermally-strengthened glass also provide evidence of the much greaterstored energy in thermally-strengthened glass. FIG. 3 illustrates across-sectional stress profile, including a central tensile stressregion 105 and a peripheral compressive stress region 106, for a thin(e.g., 1 mm) piece of chemically-strengthened glass 100 and a thicker(e.g., 3 mm) piece of thermally-strengthened glass 100′, along with arespective break pattern for each of the chemically-strengthened andthermally-strengthened glass. The thermally-strengthened glass has amuch higher level of stored energy and much larger tension force in thecentral tensile stress region 105 (as represented between dotted lines)of the glass. The different break patterns highlight the differentamounts of stored energy. The break pattern for thechemically-strengthened glass has larger cracks and patterns than thebreak pattern for the thermally-strengthened glass. The break pattern inthe thermally-strengthened glass has much smaller breaks, which isindicative of the much higher level of stored energy in the thickerthermally-strengthened glass versus the thinner chemically-strengthenedglass.

In the present invention, laser energy can be applied to thestrengthened glass substrate under conditions effective to cut thestrengthened glass substrate. In some embodiments the laser energy isfocused on or in proximity of a first surface of the strengthened glasssubstrate under conditions effective to cut the thermally-strengthenedglass substrate. Conditions effective to cut the strengthened glasssubstrate can include conditions defined by the pulse energy, pulserate, pulse duration, laser wavelength, focus depth, pulse trainfrequency, number of pulses in a pulse train, frequency of repeating thepulse train, laser beam width, distance between laser pulses on theglass substrate, and others.

In some embodiments a laser filamentation process is used to cut thestrengthened glass substrates as disclosed herein. Publication No. WO2012/006736 to Filaser Inc. (“Filaser”) discloses a laser filamentationprocess for cutting glass, the disclosure of which is incorporatedherein in its entirety. Filaser does not disclose cutting strengthenedglass.

The laser filamentation process can include irradiating the substratewith a focused laser beam. Laser filamentation can include thepropagation of an ultra-short, high peak power laser pulse that is ableto propagate over extended distances while keeping a narrow beam width.Without being bound by theory not explicitly recited in the claims, thefundamental physics of laser filamentation involves the balancingactions between Kerr self-focusing of the laser pulse andself-de-focusing due to the generated weak plasma. In order to observe alaser filament in a given media, the peak power of the laser pulseshould be higher than a critical power Pc, at which the index ofrefraction of the material interacting with the core part of the pulseincreases enough to compensate for linear diffraction. Furthermore, tosustain a filament over a long distance, the power of the laser pulseshould additionally compensate for the nonlinear diffraction caused bythe ionization of the optical medium. With an appropriately chosen laserpower, pulse length, and beam direction, a single pulse focused inproximity to or within a glass substrate can produce a filament traceperpendicular to the surface of the glass. The filament trace can extendthrough the entire thickness or only a certain percentage of thethickness, depending on the laser settings. For example, with an IFRITor Cyber laser producing laser light at 780 nm with a pulse duration of172 femtoseconds, a single pulse of around 15 μJ to 40 μJ can produce alaser filament in 0.7 mm thick display glass.

The critical power to be used to produce a self-focusing pulse can becalculated and is a function of the wavelength, the index of refractionof the optical medium and the Kerr non-liner index of refraction. Usinglaser filamentation to cut glass can greatly increase glass cuttingspeeds, for example to around 500 mm/s or higher. An array offilamentary modification lines can be produced using a high pulse rateand moving the substrate relative to the laser beam. The array offilamentary modifications can be produced with a period on the micronscale, along which the glass substrate can be cleaved by applying aslight mechanical force. The spacing and the depth of the laser filamentinduced modification can be optimized based on the glass thickness andcomposition. In the context of glass cutting, the characteristics of thefilament traces, such as spacing, depth, and width have a direct impacton the amount of force necessary to separate the pieces of glass as wellas the quality of the cut edge, and therefore the strength of the cutpiece of glass. For display glass of 0.7 mm thick, filamentary damagetraces having a diameter of a few microns and spaced with a 10 μm periodis sufficient to allow for easy cleaving. Longer periods can also workbut cleaving can be more difficult. For improved edge strength and edgequality a smaller spacing could in fact be necessary.

A laser filament produced in glass can create a small filament volume orself-focal volume wherein the glass is ionized. This volume can be verynarrow, e.g. on the order of a few microns or less. The extremely narrowvolume can be small enough to prevent strengthened glass, such asthermally-strengthened glass, from exploding during the laser cuttingprocess. The laser parameters can be selected to create a filamentwithin the substrate. The filaments can be used to form an array oflines defining a path for cleaving the substrate. After irradiating thesubstrate with laser energy, the substrate can be “cut” or fullyseparated by applying modest mechanical force. The laser processconditions described herein can be selected and optimized to cut thestrengthened glass substrate. The laser settings can be tuned to producean array of filament traces in the strengthened glass that allow forcleaving the glass without exploding and ensuring that the cut pieces ofglass meet specific strength standards. One or more pulses of laserenergy can be used to create each filament.

FIG. 4 illustrates a schematic of laser focus positions on astrengthened glass substrate 100 in accordance with some embodiments.FIG. 4 illustrates an incident laser 500 having first focal position,Focus 1, which is within a compressively strained region 106 of thestrengthened glass substrate 100. Alternatively, an incident laser 500can have a second focal position, Focus 2, which is illustrated asadjacent to a first surface 101 of the strengthened glass substrate 100.The focal points illustrated by Focus 1 and Focus 2 can be used tocreate a filament of laser light 510 in the strengthened glass substrateas shown in FIG. 4.

In some embodiments the laser can be focused in a compressively stressedregion (e.g., 106 as depicted in FIG. 4) of the strengthened glass.Generally, it is desirable to avoid focusing the laser in the tensilestrained region (e.g., 105 as depicted in FIG. 4) of the glass substrateto avoid creating a defect or crack that can propagate uncontrollably.In some embodiments the laser can be focused on a surface (101, 102 asdepicted in FIG. 4) of the strengthened glass or in proximity of thesurface (101, 102 as depicted in FIG. 4) of the strengthened glass. Insome embodiments the laser can be focused on films or layers on thesurface of the strengthened glass.

FIG. 5 illustrates a schematic of laser energy applied to a strengthenedglass substrate 100 in accordance with various embodiments of theinventions. FIG. 5 also illustrates schematic representations of anumber of laser process conditions. A pulse train or burst can bereferred to as one or more pulses in quick succession. In someembodiments the pulse train can include a number of pulses ranging fromone laser pulse to about 15 laser pulses. In some embodiments the pulsetrain can include a number of pulses ranging from one laser pulse toabout 5 laser pulses. The pulse train can be used to create a singlelaser light filament. In some embodiments the laser energy pulses in thepulse train can be repeated at a pulse burse frequency ranging fromabout 100 kHz to about 100 MHz. The time between separate pulse burstsdefines a burse repetition period (BRP). The strengthened glasssubstrate can be moved relative to the laser during application of thepulse train to the substrate. The pulse train can produce a singlefilament even with movement of the substrate because of the relativefast repetition of the pulses within a pulse train and the relativelyhigh pulse burse frequency relative to the motion of the substrate. Forexample, each of the pulses in the pulse train can overlap relative to aposition on the surface of the strengthened glass.

In the embodiment illustrated in FIG. 5, conditions for producing afilament are: the material is substantially transparent to the laserwavelength (which is in the range of 250 nm to 1000 nm); the pulse burstfrequency is in the range of 100 kHz to 100 Mhz; the pulse duration isin the range of 1 femtosecond to 100 picoseconds (preferably in therange of 10 femtoseconds to 10 picoseconds); the number of pulses perburst is in the range of 1 to 15; and the single pulse energy is in therange of 1 μJ to 100 μJ. In the embodiment of FIG. 5, conditions forproducing an array of filaments are a burst repetition frequency in therange of 100 Hz to 1 Mhz and a substrate/laser speed of 1 mm/s to 2000mm/s.

The wavelength of the laser can be varied. In some embodiments applyinglaser energy includes applying a pulsed laser having a wavelength ofabout 250 nm to about 1100 nm.

The pulse duration can be varied. In some embodiments the pulse durationranges from about 1 femtosecond to about 100 picoseconds. In someembodiments applying laser energy includes pulsing laser energy with apulse duration ranging from about 10 femtoseconds to about 100picoseconds. In some cases the pulse duration ranges from about 10femtoseconds to about 10 picoseconds.

The energy in a single laser pulse can be selected based on thethickness and composition of the glass. For some glasses, thicker glassrequires higher pulse energy. In some embodiments, applying laser energycomprises applying a pulsed laser having a pulse energy of about 1 μJ toabout 400 μJ. In some embodiments, applying laser energy comprisesapplying a pulsed laser having a pulse energy of about 1μJ to about 200μJ. In some embodiments, applying laser energy comprises applying apulsed laser having a pulse energy of about 1 μJ to about 100 μJ. Insome embodiments, the energy for a single pulse can be from about 1 μJto about 50 μJ.

The beam width of the laser can be varied. In some embodiments the beamwidth is less than about 20 μm. In some embodiments the beam width canbe from about 0.5 μm to about 10 μm. In some embodiments the beam widthcan be from about 0.5 μm to about 5 μm.

The pulse bursts or trains can be repeated at a desired frequency. Insome embodiments the pulse train is repeated at a frequency of about 100Hz to about 1 MHz. The frequency for repeating each of the pulsebursts/trains can also be expressed as the burst repetition period,which is the inverse of the frequency for repeating the pulsebursts/trains. The pulse in a first pulse train can apply laser energyto a first position on the strengthened glass substrate. The pulses in asecond pulse train can apply laser energy to a second position on thestrengthened glass substrate. The pulse trains can be used to applylaser energy to the substrate to produce a filament pattern along adesired cut line in the strengthened glass substrate. The frequency forrepeating the pulse train can be selected in combination with therelative movement between the laser and glass substrate to achieve adesired separation between the laser filaments.

In some embodiments the glass substrate is translated relative to thelaser. In some embodiments the laser is translated relative to the glasssubstrate. The glass substrate and laser are moved at a speed of about 1mm/s to about 2000 mm/s relative to each other. The translation speed ofthe laser or substrate can be selected in combination with the laserparameters to achieve a desired distance between the laser filaments onthe strengthened glass substrate. In some embodiments the applied laserenergy is translated relative to a surface of the strengthened glasssubstrate at a speed ranging from 100 mm/s to 5000 mm/s.

FIG. 6A illustrates a cross-sectional view of a illustrative laminate,such as an electrochromic device 20 including two electrochromiccomposites 10, 10′, each of which comprises a strengthened glasssubstrate with an electrochromic layer, such as a cathodic or anodicelectrochromic layer (see FIG. 1), where such composites 10, 10′ arelaminated together, for example, by a polymer layer 15. The polymerlayer 300 can comprise an ion conducting material in electroniccommunication with each of the anodic and cathodic electrochromiclayers. The electrochromic device 20 can, in preferred embodiments, beprovided as a mother glass composite 400. The mother glass composite 400can comprise an integrated (continuous) large area electrochromic device20, or alternatively can comprise an array of two or more spatiallydiscrete electrochromic devices, each comprising a correspondingspatially discrete portion of a large strengthened glass substrate. Themother glass composite 400 can be cut into smaller device sizes using alaser (e.g., a laser filamentation process) according to the methodsdescribed herein, as illustrated in FIG. 6 to form two or more spatiallydiscrete electrochromic devices (e.g., illustrated as 20-1, 20-2, 20-3,20-4) each having desired device shapes. In some embodiments, laserenergy can be applied to an electrochromic device using two or morelasers. In some embodiments, laser energy can be applied to anelectrochromic device (e.g., to a motherglass substrate comprising anelectrochromic device) using one or two lasers by focusing laser energyon or in proximity of a surface of a first strengthened glass substrate(e.g., surface 102 of substrate 100, FIG. 1B). In an alternativeapproach, laser energy can be applied to an electrochromic device (e.g.,to a motherglass substrate comprising an electrochromic device) using afirst laser focusing laser energy on or in proximity of a surface of afirst strengthened glass substrate (e.g., surface 102 of substrate 100,FIG. 1B) and a second laser focusing laser energy on or in proximity ofa surface of a second strengthened glass substrate (e.g., surface 201 ofsubstrate 200, FIG. 1B).

FIG. 6B is a schematic illustration of a method for cutting laminatessuch as electrochromic composites or electrochromic devices assembledfrom glass substrates in accordance with an embodiment. Glass substrates100, 200 are provided and patterned with electrodes (electrodes are notdepicted in the figures). The glass substrates having patternedelectrodes, represented as 100′, 200′ can be coated with active layers,such as an electrochromic anode 120, electrochromic cathode 220, and ionconductor 300. The glass substrates with anode and cathode can then beassembled as a laminate composite with an ion conductor to form a motherglass composite 400 (e.g., comprising one or more electrochromicdevices). The assembled mother glass composite 400 can then be cut intoindividual panels such as individual electrochromic devices 20-1, 20-2,20-3 using the laser filamentation processes described herein.

In some embodiments, after applying laser energy and additionally oralternatively, while applying laser energy, a force is applied to thestrengthened glass substrate to controllably separate the strengthenedglass substrate. The force can be applied by machine, hand, or theweight of the glass. The substrate can be controllably separated orcleaved along the line or area where laser energy was applied to thestrengthened glass. The glass substrate can be controllably separatedalong the filamentation pattern.

The laser conditions can be selected to result in an improved edgequality and strength in the cut pieces. The strength of glass is not asimple value. Glass is a brittle material which fails due to thepresence of defects present in the bulk, on the surface, or around theedges. The ASTM C158-02 describes a standard method for testing themodulus of rupture of glass using a four point bending test and a samplesize of around 30 specimens. It further suggests reporting the averagevalue of the modulus or rupture for the group and the standard deviationestimate of the mean. However, for mechanical design purposes, thesevalues are typically quite insufficient. It is usually important to havean idea of the probability of failure for a given stress. Moresophisticated ways of describing the strength of glass relies onphysical-based probability models. One of the most common, and simplemodels uses a Weibull probability function to describe the distributionof failure stresses. The basic, two function Weibull model giving thefailure probability F of a glass specimen is: F(σ)=1−exp[−(σ/σ₀̂m)]where F(σ) is the probability of failure of a specimen under test at thestress sigma, m is the Weibull modulus which describes the homogeneityof the flaw distribution and σ₀ is the characteristic strength(F(σ₀)=63.21%). By plotting In(In(1/1−F)) vs. In(σ) it is straightforward to determine m and σ). It should be noted that this type ofsimple model does not always fit well with the test data because testconditions such as temperature, humidity, glass composition, edgequality, load rate, etc. can have significant influence on the modulusof rupture in which case more complicated models should be used. Forapplications such as solar panels and tintable glass, it is desired tohave a low probability of rupture at stress levels typically experiencedby the product when installed in the field or on a building. Heatstrengthened glass and tempered glass usually meet that requirement witha probability of failure <5% for stresses up to around 40 MPa. For fullytempered glass, stress up to around 100 MPa can be tolerated at the 5%probability number. The methods disclosed herein for cutting thermallystrengthened glass with a laser can yield at least one cut piece meetingthe aforementioned strength characteristic. In some embodiments at leastone of the cut pieces has a modulus of rupture of greater than about 40MPa. In some embodiments at least one of the cut pieces has a modulus ofrupture of greater than about 100 MPa. In some embodiments the piece ofcut glass has a probability of failure of less than about 5% under a 40MPa load or 100 MPa load. In some embodiments two or more cut glasspieces have a Weibull modulus greater than 10. For assessing theprobability of failure for a given force or load a set of cut glasspieces can be tested.

In some embodiments the cut edges can be further strengthened aftercutting. In some embodiments laser energy is applied to the cut edge tostrengthen the cut edge. In some embodiments a chemical treatment isperformed to the cut edge or glass substrate. In some embodiments acoating is applied to the cut edge, for example, the coating cancomprise a metal, an oxide, or a polymer.

FIG. 7 is a schematic illustration of a laser edge treatment of a glasssubstrate 100 in accordance with an embodiment. Laser energy 550 can beapplied to the cut edge to form a chamfered edge. The chamfered edge canreduce or remove residual stress at the edge of the glass to furtherstrengthen the cut glass edge. This process can be repeated foradditional angles as shown in FIG. 7A to create an edge with a smootherprofile. As the number of angles increases the edge better approximatesa pencil edge profile, with a diameter equal or larger than the glassthickness. Such a pencil-like edge can reduce or remove residual stressat the edge of the glass to further strengthen the cut glass edge. FIG.7B is a schematic illustration of a laser edge treatment of two glasssubstrates 100 in accordance with an embodiment. When the laser edgetreatment of FIG. 7B is applied to a glass substrate, there may be no orlittle residual stress at the edge of the glass. The glass substrates100 are illustrated as separated by a polymer interlayer. Other layerscan be between the glass substrates 100. FIG. 7C is a schematicillustration of a laser cutting a glass substrate 100 and concurrentlyperforming an edge treatment on the cut edges in accordance with anembodiment. The laser energy 550 can be applied to cut the piece ofglass to form two cut edges and simultaneously or concurrently chamferthe two cut edges. A chamfered edge may provide better durability onsome applications.

FIG. 8 is a schematic illustration of a polymeric edge treatment of aglass substrate 100 in accordance with an embodiment. The polymeric edgetreatment can include coating the edge with a layer 600 of a polymermaterial. Examples include poly-methacrylates, epoxies, polyurethanes,poly-silicones, poly-iso-butylenes, etc. FIG. 8A illustrates a polymeredge coating 600 (such as polyurethanes, poly-iso-butylenes,poly-silicones, etc.) for a glass edge having a smoother profile, suchas the edge profile of the glass substrate illustrated in FIG. 7A.

FIG. 9 is a schematic illustration of a chemical edge treatment of aglass substrate 100 in accordance with an embodiment. An example of achemical edge treatment includes treating the edge with an etchant 700such as hydro fluoric acid. The hydrofluoric acid treatment can removemicrocracks in the edge to strengthen the cut edge. FIG. 9A illustratesa chemical edge treatment 700 for a glass edge having a smootherprofile, such as the edge profile of the glass substrate illustrated inFIG. 7A. The chemical edge treatment can remove eventual microcracks tofurther increase edge strength.

The edge treatment of glass is a critical step in the process ofpreparing glass for architectural and transportation applications. Glasssheets are edge treated after being cut to remove defects on the cutedge, such as indents, chips, teeth, grooves, etc. A high-quality anddefect-free edge is one of the main factors preserving the strength ofglass during processing and further use. For example, edge treatment isrequired to prevent fracture of the glass during thermal strengtheningand for this reason edging is always performed before this operation.Edge treatment also prevents spontaneous fracture of the glass as aresult of thermal shock and fracture of the glass under loads occurringduring service, such as loads due to wind and snow. The need to assureacceptable edge quality makes it necessary to develop new cuttingtechnologies and improve existing ones. A widespread process for edgetreating glass is diamond wheel edge grinding. However, as explained byPopov (Glass and Ceramics, Vol. 67, Nov. 7-8, 2010) “Edge grinding isthe most critical and laborious technological operation in theproduction of objects made of plate glass”. Therefore, cutting methodsthat additionally provide an edge with acceptable edge quality aredesired and disclosed herein.

Ground edges as illustrated in FIG. 11 display a crack free smoothsurface. The texture results from small pits which vary in depthdepending on the grinding conditions. Specifically, fine ground edgestypically display pits with depth around 1.5 μm to 2.5 μm (See, Glassand Ceramics, Vol. 13, Issue 12, December 1956).

Strengthened glass, such as thermally-strengthened glass, is typicallyedge treated prior to strengthening. Therefore, the current paradigm forpreparing thermally strengthened glass is to first cut the glass tofinal the size, edge treat the glass, and then thermally strengthen theglass. In contrast, in some embodiments of the invention: large piecesof glass (motherglass) are thermally strengthened, coatings andadditional processes can be performed on the motherglass, and finally,the motherglass can be simultaneously cut and edge treated to provide acut piece of glass with acceptable strength for use in architectural andtransportation applications.

FIG. 12 is a schematic illustration of chemical strengthening a stack oflaser cut strengthened glass substrates (or composites or devicescomprising such substrates—e.g., 10, 20 FIG. 1), in accordance with anembodiment—for example, as another approach for strengthening a cutedge. One or more cut strengthened glass substrates (or composites ordevices comprising such substrates) can be submerged in a bathcontaining a chemical strengthening agent 750, for example, moltenpotassium salt to chemically strengthen the cut substrate.

In some embodiments, a feature of laser filamentation in glass is themodification that occurs locally, around the filamentation volume. Thelocal modification can leave a fingerprint, pattern, or indicia on thecut edge of the glass. The heat from the filament induces a localizedmodification that can result in a very finely textured surface. Byproducing filamentation volumes that nearly overlap, a uniform, smoothtexture can be created. It is not necessary for pure cutting purposes tohave a very fine spacing of the filamentation traces, as shown in“Display glass cutting by femtosecond laser induced single shot periodicvoid array” by Sumiyoshi. Sumiyoshi shows that a void array can beproduced in glass to guide the cleavage of the glass. In the case ofSumiyoshi, the resulting cut edge is not uniformly smooth and crackspropagate from filament void to filament void during the cleavage step.The preferred method disclosed herein produces a cut edge surface asshown in FIG. 18, in which the cut edge presents a large area of uniformfinely textured glass. In the embodiment of FIG. 18, the desired texturecovers about 80% of the edge but the laser power can be increased toproduce filamentation modification along the whole surface. By providinga high edge quality, the cut piece of glass of strengthened glassmaintains its high strength.

The laser processes described herein can leave a fingerprint on the edgeof the cut strengthened glass. Laser filamentation and cleaving canleave a fingerprint, pattern, or indicia on the edge of the cut glassthat is unique to the cutting process and laser parameters. For example,the cut edge of the glass can have indicia of a laser filamentationcutting process. The indicia can be a series of a plurality offilamentation traces. In some embodiments, the indicia of a laserfilamentation cutting process comprises a filamentation pattern definedby a series of regularly recurring substantially parallel filamentationtraces. In some embodiments the filamentation traces are orientedsubstantially perpendicular to the first surface of the glass and secondsurface of the glass opposing the first surface. Devices or compositesincluding a cut strengthened glass substrate with the fingerprint orindicia of the laser process are disclosed herein. The indicia of thelaser process can be imaged using optical microscopy. The indicia caninclude areas where laser filament traces are visible and other areasthat may appear smooth or not visibly include a portion of a filament.Examples of the indicia are shown in FIGS. 13A, 13B, 14, and 16-19. FIG.13A is a schematic illustration of a glass substrate, not drawn toscale, showing indicia of a laser filamentation process. The indiciainclude filament line traces 900. The filament line traces 900 have awidth 901 and length 902. The filament line traces 900 have an aspectratio defined by the ratio of the length 902 to the width 901 of thefilament line trace 900. The adjacent laser filament traces can beseparated by a distance 903.

In some embodiments the filamentation traces extend from the firstsurface of the glass towards the second surface of the glass opposingthe first surface. The traces extend along the cut face of the glassfrom the first surface towards the second surface of the glass. In someembodiments each of the filamentation traces extend from the firstsurface toward the second surface to a depth of at least 75% of thethickness of the glass. In some embodiments each of such filamentationtraces extend from the first surface toward the second surface to adepth of at least 90% of the thickness of the glass. In some embodimentseach of such filamentation traces extend from the first surface towardthe second surface to a depth of at least 95% of the thickness of theglass. In some embodiments each of such filamentation traces can extendsubstantially the entire thickness of the glass.

The distance separating filamentation traces can vary. The laser pulserepetition (e.g. train/burst frequency) and translation speed and otherparameters can be selected to achieve a desired separation betweenadjacent filamentation traces. In some embodiments the distance betweenadjacent filamentation traces is about 0.1 μm to about 40 μm. In someembodiments the distance between adjacent filamentation traces is about1 μm to about 20 μm. In some embodiments the distance between adjacentfilamentation traces is about 1 μm to about 10 μm. In some embodimentsthe distance between adjacent filamentation traces is about 1 μm toabout 5 μm.

The filamentation traces can have a visible aspect ratio. Thefilamentation traces have a filamentation trace length and afilamentation trace width with a filamentation trace aspect ratiodefined by the ratio of the filamentation trace length to thefilamentation trace width. In some embodiments the filamentation tracehas an aspect ratio of greater than about 5:1. In some embodiments thefilamentation trace has an aspect ratio of greater than about 10:1. Insome embodiments the filamentation trace has an aspect ratio of greaterthan about 20:1. In some embodiments the filamentation trace has anaspect ratio of greater than about 50:1. In some embodiments thefilamentation trace has an aspect ratio of greater than about 100:1. Insome embodiments the filamentation trace has an aspect ratio of greaterthan about 200:1. The aspect ratio can refer to the aspect ratio for asingle filament trace or an average of a sample of filament traces. Forexample the aspect ratio for a set of 5, 10, or 20 filament traces canbe determined and averaged.

In some embodiments the filamentation traces can have a width of about0.5 μm to about 10 μm. In some embodiments the filamentation traces canhave a width of about 0.5 μm to about 5 μm. In some embodiments thefilamentation traces can have a width of about 0.5 μm to about 3 μm. Insome embodiments the filamentation traces can have a width of about 1 μmto about 3 μm. In some embodiments the filamentation traces can have awidth of about 1 μm to about 5 μm. The width of the filamentation tracecan be determined using optical microscopy. The width of a singlefilamentation trace can be measured or a set of filamentation tracewidths can be measured and averaged. For example a set of 5, 10, or 20filamentation traces can be measured and averaged.

In some embodiments the filament traces can overlap in regions. Forexample, the filament traces can overlap to create a surface that has aground-like surface that is free of “cracks”, or textured to look likere-melted glass. In some embodiments greater than about 70% of the cutedge surface can have the filament line traces and textured surface ofthe laser indicia described herein, as shown in FIG. 18. The indiciashown in FIG. 16 is different than the smooth surface shown in FIG. 16that would be obtained from cleaving glass by the propagation of acrack.

The indicia of the laser filamentation cutting process can becharacterized by a surface roughness. In some embodiments the laserfilamentation process can result in a cut face with a surface roughnessof less than 20 μm root mean square (“rms”). In some embodiments thelaser filamentation process can have a surface roughness of less than 10μm rms. In some embodiments the laser filamentation process can have asurface roughness of less than 5 μm rms. In some embodiments the laserfilamentation process can have a surface roughness of less than 2 μmrms.

Examples of images of the laser indicia are shown in FIGS. 13B and 14.FIGS. 13B and 14 show examples of laser filamentation cut indicia on thesurface of the glass with parallel laser trace lines that areperpendicular to the surface of the glass. The illustrated laserfilamentation fingerprint shows parallel laser filamentation traceshaving a thickness of about 1 μm with the spacing between the traces ofabout 2 to about 3 μm. A spacing between the traces may also be about 4μm.

FIGS. 16-19 show additional examples of the laser indicia describedherein. FIG. 16 illustrates a cut edge of a thermally tempered glasswith laser indicia showing filamentation traces of about 168 μm and 221μm long. The periodicity of the laser filamentation traces is alsoillustrated with a distance of about 10 μm between filamentation traces.FIG. 17 illustrates a 50× magnification of the cut edge of fullytemperature glass. The visible laser filamentation traces have lengthsof 20 μm and greater and a high aspect ratio. The periodicity of thelaser filamentation traces is also illustrated with a distance of about10 μm between three filamentation traces. FIG. 18 illustrates a cut edgeof a thermally strengthened glass with laser indicia over greater thanabout 70% of the thickness of the cut edge. Laser indicia of FIG. 18includes laser indicia that are about 542 μm long. FIG. 19 illustratesfilamentation traces that are visible and extend over a long distance,e.g. about 800 μm although some filamentation traces morph and produce aground like texture. The spacing between a set of traces in FIG. 19 isabout 7 μm.

In some embodiments the laser energy can be applied using two or morelasers. The laser energy can be applied to the same surface of thesubstrate. In some embodiments, one laser applies laser energy to afirst surface of the substrate and a second laser applies laser energyto a second surface of the substrate opposing the first surface. In someembodiments multiple lasers are apply energy along the same cut line.The multiple lasers can scan the cut line simultaneously or can scan thecut line in a staggered configuration. The multiple lasers can be usedto apply energy to different areas of the glass substrate. In someembodiments three lasers are used with one laser providing afilamentation cut line, one laser providing a first edge filamentationchamfer line and one laser providing a second edge filamentation chamferline.

In some embodiments a single pass with the laser is sufficient. In someembodiments, multiple passes are used to cut the strengthened glasssubstrate.

The edges produced by the laser filamentation process are high qualityand do not require post processing like grinding or smoothing. FIGS.13B, 14 and 16-19 show high edge quality and a lack of cracks on theedge surface. In contrast, FIG. 15 is a picture of a glass edge that hasbeen mechanically cleaved and shows cracks on the edge surface.

Various types of glass can be cut using the methods disclosed herein.The glass to be cut can be referred to generally as a substrate, lite,or motherglass. Examples of glass include soda-lime glass, borosilicateglass, alumino-silicate glass, alumino-borosilicate glass, etc. Theglass can be chemically or thermally-strengthened.

A coated glass substrate can include an inorganic single or multi-filmcoating. Examples of coated soda-lime glass include double silver andtriple silver low-e coated glass, anti-reflective coated glass, andfluorine doped tin oxide (FTO) coated glass.

Higher thermal expansion glass substrates are more difficult to cut witha laser process as local thermal gradients in the glass can generatelocal stresses and result in breaking. It is desirable to have a cuttingprocess that induces low thermal heating of the glass to enable cuttingof high thermal expansion glasses. It is significant that glass havingmoderate to high coefficients of thermal expansion can be used with themethods disclosed herein. In some embodiments the strengthened glasssubstrate has a coefficient of thermal expansion of greater than 4×10-6per ° K. In some embodiments the strengthened glass substrate has acoefficient of thermal expansion of greater than 7×10-6 per ° K. In someembodiments the strengthened glass substrate has a coefficient ofthermal expansion of greater than 9×10-6 per ° K. In some embodimentsthe strengthened glass substrate has a coefficient of thermal expansionof less than 4×10-6 per ° K. Borosilicate glass typically has acoefficient of thermal expansion of about 3.3×10-6 per ° K. Soda-limeglass typically has a coefficient of thermal expansion of about9-9.5×10-6 per ° K.

In some embodiments the thermally strengthened glass substrate has astored energy per unit area greater than the stored energy per unit areain a chemically strengthened glass.

In some embodiments the strengthened glass substrate includes a firstsurface having a first compressively stressed surface region, anopposing second surface having a second compressively stressed surfaceregion, and an internal center region between the first and secondcompressively stressed surface regions. The first compressively stressedsurface and the second compressively strained surface can each have athickness of greater than about 250 mm.

Glass substrates of varying thicknesses can be used with the methodsdisclosed herein. In some embodiments, glass substrates with a thicknessof about 1.0 mm or greater can be used. In some embodiments glasssubstrates with a thickness of at least about 1.6 mm can be used. Insome embodiments glass substrates with a thickness of about 2.0 mm orgreater can be used. In some embodiments glass substrates with athickness of greater than 2.2 mm can be used. In some embodiments glasssubstrates with a thickness of greater than 3.0 mm can be used. In someembodiments glass substrates with a thickness of greater than 4.0 mm canbe used. In some embodiments glass substrates with a thickness ofgreater than 6.0 mm can be used.

Thermally-strengthened glass substrates typically have a thickness ofgreater than about 1.0 mm. In some embodiments a thermally-strengthenedglass substrate with a thickness of greater than about 1.5 mm, greaterthan about 1.6, greater than about 2.0 mm, greater than about 2.0 mm, orgreater than about 3 mm, greater than about 4 mm, or greater than about6 mm is used. Examples of heat-strengthened glass substrate thicknessesinclude 1.5 mm, 1.6 mm, and 3.2 mm, 4.0 mm, and 6.0 mm.

In some embodiments glass substrates with a thickness of less than about1.0 mm can be used. Chemically-strengthened glass substrates can have athickness of less than about 1.0 mm, especially for applications likemobile devices. Examples of chemically-strengthened substratethicknesses include 0.3 mm, 0.5 mm, and 0.7 mm.

The size of the glass processed using the laser cutting methodsdisclosed herein can vary. Standard glass sizes can be used. Examples ofvarious standard glass substrate sizes include 1.1 m by 1.3 m, 1.5 m by3 m, 2.2 m by 2.6 m, and 3 m by 6 m. In some embodiments the glasssubstrate has a surface area of at least about 0.25 m². In someembodiments the glass substrate has a surface area of at least about 1m². In some embodiments the glass substrate has a surface area of atleast about 4 m². In some embodiments the glass substrate has a surfacearea of at least about 6 m². In some embodiments the glass substrate hasa surface area of at least about 18 m².

Applications for chemically-strengthened glass include mobile devicessuch as cell phones, smart phones, and tablet computers.Chemically-strengthened glass is typically cut into smaller sizesappropriate for phone screens and tablet computer screens. Theapplications disclosed herein use larger cut pieces than the sizestypically used for mobile devices. In some embodiments, the glasssubstrate is cut into one or more pieces with at least one of the pieceshaving a surface area of greater than about 0.25 m². In someembodiments, the glass substrate is cut into one or more pieces with atleast one of the pieces having a surface area of greater than about 0.5m². In some embodiments, the glass substrate is cut into one or morepieces with at least one of the pieces having a surface area of greaterthan about 1.0 m². In some embodiments, the glass substrate is cut intoone or more pieces with at least one of the pieces having a surface areaof greater than about 2 m². In some embodiments, the glass substrate iscut into one or more pieces with at least one of the pieces having asurface area of greater than about 5 m².

In some embodiments the methods disclosed herein can be used to cut astrengthened glass substrate without any coatings.

In some embodiments the glass substrate can support one or more films,layers, glazings, and coatings. The layers can include thin films. Thefilms can be generally coplanar. The films described herein can be incontact with the glass substrate or in contact with one or more otherfilms supported by the glass substrate. In some embodiments thestrengthened glass substrate supports two or more layers in asubstantially parallel planar relation to the glass substrate and eachother. In some embodiments the two or more layers are adjacent to asurface of the glass substrate or a surface of another of the two ormore layers.

The laser processes described herein can be used to cut the strengthenedglass and films, layers, glazings, and coatings in the desired shape andsize. Examples of films include conducting films, oxide films, diffusionbarriers, reflective coatings, buffer layers, transparent conductingoxides, electrochromic films, ion conductor, conductive oxides,insulating films, etc.

In some embodiments the one or more films supported on the glasssubstrate can be in electronic communication with one or more otherfilms supported on the glass substrate. The films in electroniccommunication can be in direct contact with each other or there can beone or more intervening films or layers.

In some embodiments any of the devices disclosed herein can comprise orinclude any of the glass substrates described herein. In someembodiments any of the devices disclosed herein can be supported by anyof the glass substrates described herein.

In some embodiments the thermally-strengthened glass substrate supportsone or more films generally coplanar with each film in contact with theglass substrate surface or another film supported by the glasssubstrate. In some embodiments the one or more films can be formed onthe strengthened glass substrate prior to applying laser energy. Any ofthe films described herein can have one or more intervening layersbetween the substrate and the other layers described herein.

In some embodiments a glass substrate composite can be cut using theprocesses disclosed herein. In some embodiments the composite is apartially fabricated electrochromic device. The partially fabricatedcomposite can include a strengthened glass substrate having a firstsurface, an electrically conductive layer supported on the first surfaceof the strengthened glass substrate, and an electrochromic film inelectronic communication with the electrically conductive layer. In someembodiments the composite can include a chemically-strengthened glasssubstrate. In some embodiments the strengthened glass substrate is athermally-strengthened glass substrate. The electrically conductivelayer can comprise a metal or a transparent conductor such as atransparent conductive oxide. Examples of electrochromic films includetungsten oxide (W0₃), molybdenum oxide (MoO3), niobium oxide (Nb2O5),titanium oxide (TiO2), copper oxide (CuO), iridium oxide (Mn₂0₃),vanadium oxide (V₂0₃), nickel oxide (Ni₂0₃), cobalt oxide (Co₂0₃) andthe like. In some embodiments the electrically conductive layer isdirectly on the strengthened glass substrate. In some embodiments thecomposite includes one or more generally coplanar films between thefirst surface of the strengthened glass substrate and the electricallyconductive layer. For example, an electrochromic composite couldcomprise a tempered 3.2 mm thick Pilkington Tec-15 substrate with a 400nm thick tungsten oxide film coated on top of the FTO surface. In someembodiments an ion conductor is in electronic communication with theconductive layer.

In some embodiments the cut glass piece can be further processed. Insome embodiments the cut edges of the glass piece can undergo furtherprocessing, such as an edge strengthening processes. In some embodimentsthe composite is assembled in an electrochromic device after cutting thecomposite. In some embodiments the cut glass piece can be furtherassembled into an integrated glass unit. In some embodiments the cutglass piece can be further assembled into an electrochromic device.

In some embodiments methods for fabricating two or more electrochromiccomposites are provided. The methods include providing an electrochromiccomposite comprising a strengthened glass substrate having a firstsurface and an opposing second surface, an electrically conductive layersupported on the first surface of the strengthened glass substrate, andan electrochromic layer in electronic communication with theelectrically conductive layer; and applying laser energy to thestrengthened glass substrate under conditions effective to cut thestrengthened glass substrate to form two or more electrochromiccomposites. The electrochromic composite can be provided as a motherglass composite comprising an array of two or more spatially discreteelectrochromic composites, each comprising a corresponding spatiallydiscrete portion of the strengthened glass substrate. Laser energy canbe applied to the strengthened glass substrate to cut the mother glasscomposite and separate two or more spatially discrete electrochromiccomposites. The electrochromic composite can be provided as a motherglass composite comprising an array of two or more spatially discreteelectrochromic composites, each comprising a corresponding spatiallydiscrete portion of the strengthened glass substrate. Laser energy canapplied to the strengthened glass substrate to cut the mother glasscomposite to form a panel comprising two or more spatially discreteelectrochromic composites. An integrated glass unit can be assembledusing the one or more electrochromic composites cut from the motherglass composite.

In some embodiments methods for fabricating two or more electrochromicdevices are provided. The methods include providing an electrochromicdevice comprising at least one strengthened glass substrate; andapplying laser energy to the electrochromic device under conditionseffective to cut the strengthened glass substrate to form two or moreelectrochromic devices. The electrochromic device can include twoelectrically conductive layers and an electrochromic cell in electroniccommunication with the electrically conductive layers. The electricallyconductive layers and electrochromic cell can be supported, directly orindirectly, on a surface of the strengthened glass substrate. Theelectrochromic cell can include an anode, a cathode, and an ionconductor in electronic communication with the anode and cathode with atleast one of the anode or cathode comprising an electrochromic material.In some embodiments the cut electrochromic device is assembled into anintegrated glass unit.

In some embodiments the electrochromic device includes two transparentconductive oxide layers. In some embodiments the electrochromic devicecomprises a tungsten mixed metal oxide layer. In some embodiments theelectrochromic device comprises a nickel mixed metal oxide layer. Insome embodiments the electrochromic device comprises a lithium ionconducting layer. In some embodiments the electrochromic device includesa first strengthened glass substrate that is a chemically-strengthenedor thermally-strengthened glass substrate. In some embodiments theelectrochromic device includes first and second glass substrates thatare chemically-strengthened or thermally-strengthened glass substrates.

As described above in connection with FIG. 6A, in some embodiments theelectrochromic device is provided as a mother glass composite. In anapproach, the mother glass composite can comprise an integrated,spatially continuous large area electrochromic device prior to cutting.In an alternative approach, the mother glass composite can comprise anarray of two or more spatially discrete electrochromic devices prior tocutting. Each of the discrete electrochromic devices can include acorresponding spatially discrete portion of at least one commonstrengthened glass substrate. Laser energy can be applied to thestrengthened glass substrate to cut the mother glass composite andseparate the two or more spatially discrete electrochromic devices. Ananalogous approach can also be employed for fabricating two or morecomposites (e.g., electrochromic composites such as electrochromic halfcells). Accordingly, in some embodiments an electrochromic composite isprovided as a mother glass composite comprising an array of two or morespatially discrete electrochromic composites, each comprising acorresponding spatially discrete portion of at least one commonstrengthened glass substrate. Laser energy can be applied to thestrengthened glass substrate to cut the mother glass composite to form apanel comprising two or more spatially discrete electrochromiccomposites. An integrated glass unit can be assembled using one or moreelectrochromic devices cut from the mother glass composite.Alternatively, an integrated glass unit can be assembled using one ormore electrochromic composites cut from a mother glass composite.

FIG. 6A illustrates a top view of a mother glass composite 400 that iscut into four devices having different shapes. In an approach in whichthe mother glass composite 400 comprises an array of two or morespatially discrete electrochromic devices 20, each of such devices caneach include an edge periphery or a sealed edge periphery. Laser energycan be applied to the common strengthened glass substrate to cut thedevices out around the edge periphery or the sealed edge periphery ofeach device, thereby forming two or more electrochromic devices (e.g.,20-1, 20-2, 20-3, 20-4 of FIG. 6A). Alternatively, where the motherglass composite 400 comprises an array of two or more spatially discreteelectrochromic devices 20, the array may be retained as an array ofactive devices on the at least one common strengthened glass substrateto provide a large area, multi-panel device (e.g., a large area window);in such cases, the approach of the present invention may be used to cutthe strengthened glass substrate along a peripheral edge of the motherglass composite 400 (e.g., to trim the peripheral edge of suchmulti-panel device on the mother glass composite 400). In any case, thedevice edges can be sealed prior to applying laser energy or aftercutting the devices into the desired shapes. In an approach in which themother glass composite comprises an integrated, spatially continuouslarge area electrochromic device 20, the device can itself be cut toform two separate electrochromic devices (e.g., 20-1, 20-2, 20-3, 20-4of FIG. 6A). Additionally, or alternatively, the peripheral edge of suchmother glass composite 400 can be trimmed by cutting the strengthenedglass substrate along a peripheral edge of the mother glass composite400.

In some embodiments the electrochromic device comprises: a first glasssubstrate having a first surface and an opposing second surface, a firstelectrically conductive layer supported on the first surface of thefirst glass substrate, and an electrochromic anodic layer in electroniccommunication with the first electrically conductive layer, a secondglass substrate having a first surface and an opposing second surface, asecond electrically conductive layer supported on the second surface ofthe second glass substrate, and an electrochromic cathodic layer inelectronic communication with the second electrically conductive layer,and an ion-conducting material in electronic communication with each ofthe electrochromic anodic layer and the electrochromic cathodic layer.

U.S. Patent Publication No. 2012/0200908 to Bergh et al. (“Bergh etal.”) discloses examples of electrochromic coatings and devices, thedisclosure of which is incorporated by reference in its entirety herein.The electrochromic device can be made using any of the materials andmethods disclosed in Bergh et al.

In some embodiments a transparent conductive oxide layer can bedeposited on the glass substrate during the thermal strengthening step.In some embodiments the transparent conductive oxide layer is addedafter the strengthening step.

In some embodiments the electrode layer can be deposited usingsputtering. In some embodiments the electrode layer can be depositedusing a wet coating. In some cases the wet coating can be cured.Different materials can be used for the anode and cathode in theelectrochromic stack. Any of the materials disclosed in Bergh et al. canbe used for the anode and cathode in the electrochromic stack. In someembodiments the first and second electrode layers can be patterned toprovide space for a bus bar.

In some embodiments the electrochromic device includes two strengthenedglass substrates and the electrochromic device is cut using one or morelasers. In some embodiments multiple passes of the laser can be used tocut a device having two strengthened glass substrates. In someembodiments multiple lasers can be used to cut a device having twostrengthened glass substrates at the same time. In some embodiments thetwo strengthened glass substrates are cut in the same shape. In someembodiments one of the strengthened substrates can be cut in a differentsize or shape to accommodate a bus bar or the installation of anotherelectronic device.

In some embodiments methods for fabricating an insulated glass unit areprovided. The methods can include providing a first mother glasscomprising a first strengthened glass substrate; applying laser energyto the first strengthened glass substrate under conditions effective tocut the strengthened glass substrate to form a first glass lite;providing a second glass lite; and assembling the first glass lite andthe second glass lite into an insulated glass unit. In some embodimentsthe mother-glass includes thermally-strengthened glass substrate. Insome embodiments the mother-glass includes chemically-strengthened glasssubstrate. In some embodiments a second mother-glass is providedcomprising a second strengthened glass substrate. A second glass litecan be formed by cutting the second strengthened glass substrate. Insome embodiments the second strengthened glass substrate is athermally-strengthened glass substrate. In some embodiments the secondstrengthened glass substrate is a chemically-strengthened glasssubstrate.

In some embodiments the first and/or second strengthened glass substratecan be provided as a component of an electrochromic composite. Theelectrochromic composite can include an electrically conductive layersupported on a surface of the first strengthened glass substrate and anelectrochromic layer in electronic communication with the electricallyconductive layer. In some embodiments the first and/or secondstrengthened glass substrate can be provided as a component of anelectrochromic device.

In some embodiments the methods disclosed herein can be performed in aclean room or other controlled environment.

In some embodiments devices are provided including any of the cutglasses described herein. In some embodiments a piece of cut glass isprovided. The cut glass can include a thermally-strengthened glasssubstrate having a first surface, an opposing second surface, and aperipheral edge between the first surface and the second surface, theedge having indicia of a laser filamentation cutting process.

In some embodiments an electrochromic composite is provided. Theelectrochromic composite includes a strengthened glass substrate havinga first surface, an opposing second surface, and a peripheral edgebetween the first surface and second surface, the edge having indicia ofa laser filamentation cutting process; an electrically conductive layersupported on the first surface of the strengthened glass substrate; andan electrochromic layer in electronic communication with theelectrically conductive layer. The indicia of the laser filamentationprocess are described herein. In some embodiments the conductive layerdirectly contacts the first surface of the strengthened glass substrate.In some embodiments one or more generally coplanar layers can be betweenthe conductive layer and the first surface of the strengthened glasssubstrate. In some embodiments the electrochromic composite includes acoating on the peripheral edge of the strengthened glass comprisingmetal, oxide material, or a polymer layer.

In some embodiments an electrochromic device is provided. Theelectrochromic device can include at least one strengthened glasssubstrate having a first surface, an opposing second surface and aperipheral edge between the first surface and second surface, theperipheral edge having indicia of a laser filamentation cutting process.The indicia of the laser filamentation process are described herein.

The electrochromic device can include two electrically conductive layersand an electrochromic cell in electronic communication with theelectrically conductive layers with the electrically conductive layersand electrochromic cell being supported, directly or indirectly, on thefirst surface or second surface of the strengthened glass substrate. Theelectrochromic cell can include an anode layer, a cathode layer, and anion conductor layer in electronic communication with the anode andcathode layers with at least one of the anode or cathode comprising anelectrochromic material.

In some embodiments the electrochromic device comprises a first glasssubstrate having a first surface and an opposing second surface, a firstelectrically conductive layer supported on the first surface of thefirst glass substrate, and an electrochromic anodic layer in electroniccommunication with the first electrically conductive layer, a secondglass substrate having a first surface and an opposing second surface, asecond electrically conductive layer supported on the second surface ofthe second glass substrate, and an electrochromic cathodic layer inelectronic communication with the second electrically conductive layer,and an ion-conducting material in electronic communication with each ofthe electrochromic anodic layer and the electrochromic cathodic layer,at least one of the first glass substrate and the second glass substratebeing a strengthened glass substrate having a peripheral edge betweenthe first surface and second surface, the peripheral edge having indiciaof a laser filamentation cutting process.

In some embodiments each of the first glass substrate and the secondglass substrate are a strengthened glass substrate. In some embodimentseach of the first glass substrate and the second glass substrate are astrengthened glass substrate having a peripheral edge between the firstsurface and second surface with each of the peripheral edges havingindicia of a laser filamentation cutting process. In some embodiments atleast one strengthened glass substrate is a chemically-strengthenedglass substrate. In some embodiments at least one strengthened glasssubstrate is a thermally-strengthened glass substrate.

In some embodiments an insulated glass unit is provided. The insulatedglass unit can include a first lite comprising strengthened glass havinga first surface, an opposing second surface and a first peripheral edgebetween the first surface and second surface, a second lite comprisingglass having a first surface, an opposing second surface, and a secondperipheral edge between the first surface and second surface, a spacerelement providing spatial separation between the first glass lite andthe second glass lite, at least one of first peripheral edge or thesecond peripheral edge having indicia of a laser filamentation cuttingprocess. The second lite can comprise a strengthened glass lite. Thefirst and second lites can comprise chemically-strengthened glass. Thefirst and second lites can comprise thermally-strengthened glass. Thefirst lite can support one or more films generally coplanar and eachfilm in contact with the glass substrate surface or another filmsupported by the substrate. The second lite can support one or morefilms generally coplanar and each film in contact with the glasssubstrate surface or another film supported by the substrate. The firstand/or second lite can include an electrochromic material or support anelectrochromic cell or an electrochromic device.

Example 1

A glass substrate for use in a window is first heat strengthened toreach the necessary surface stress for the final window product. In mostcases a surface stress of around 65 MPa is sufficient but this can varydepending on the installation location and other factors. The glasssubstrate is then coated with a first layer of an electrochromic film.The first layer of the electrochromic film can be cured at a temperatureof less than 300° C. Some processes do not require a cure post coating,for example sputtered electrochromic layers do not typically require athermal treatment after deposition. In parallel, a matching counterelectrode electrochromic layer is coated on another strengthened glasssubstrate of equal size to the first glass substrate. The counterelectrode electrochromic layer may be cured or not cured.

The two coated strengthened glass substrates are then laminated togetherwith a polymer between the two glass substrates which has the necessaryion conductivity properties to make a functional electrochromic device.

The resulting electrochromic window can then be cut down to a number ofdifferent sizes and shapes to meet customer demand. The cutting is donewith a laser cutting system that is optimized to cut the electrochromicwindow comprising strengthened glass. The laser cutting process is alaser filamentation process which consists in irradiating the windowwith laser energy along a desired cut line. The laser settings areoptimized to produce a filamentary interaction within the thickness ofboth pieces of glass forming the electrochromic window. The laserinteraction is contained within a very narrow volume which prevents theglass from shattering during the process. The window is then cleaved orseparated along the cutting line. Repeating these processes at differentangles and suitable locations it is possible to create a cut edge on alaminated part that is chamfered. By further repeating this process itis possible to create a cut edge on a laminated part that approximates acylindrical or pencil edge. See FIG. 7B.

Example 2

A soda-lime glass substrate is provided. The soda-lime glass isprocessed to add a transparent conducting oxide (TCO) layer during thethermal-strengthening process. The soda-lime glass undergoes a customhigh temperature TCO process where the glass reaches a temperature ofaround 650° C. The substrate is subsequently cooled at a rate thatinduces a surface stress of around 60 MPa. The TCO-coated,heat-strengthened glass is then coated with an electrochromic coatingand calcined at a temperature of around 300° C. for around 1 hour.

The thermally-strengthened glass substrate can then be assembled into alarge device with a strengthened glass pair using a polymer ionconductor between the two pieces of strengthened glass. The assembleddevice is then cut down into the desired smaller device sizes using thelaser filamentation processes described herein.

Example 3

A 3.2 mm soda-lime glass substrate from Pilkington (TEC-15 TQ) iscleaned, heat-strengthened or tempered and then cleaned again. Aftercleaning, the substrate is coated with a cathode solution usingslot-coating, spray coating, or dip coating. The wet coated cathode filmis subsequently dried using air, heating, vacuum, or a combination orsequence of these methods. After the film is dried the cathode film isheated to a temperature between about 250° C. and about 550° C. in acontrolled environment, e.g. clean dry air, to create the desiredcathode material.

A second 3.2 mm soda-lime glass substrate from Pilkington (TEC-15 TQ) iscleaned, heat-strengthened or tempered and then cleaned again. Aftercleaning the substrate is coated with an anode solution usingslot-coating, spray coating, or dip coating. The wet coated cathode filmis subsequently dried using air, heating, vacuum, or a combination orsequence of these methods. After the film is dried the cathode film isheated to a temperature between about 250° C. and about 550° C. in acontrolled environment, e.g. clean dry air, to create the desired anodematerial.

The cathode coated glass substrate is then coated with a polymeric ionconductor film using a stencil printing or screen printing process. Thispolymer film may require a thermal or vacuum drying step or a thermal orUV curing step post coating. Optionally, the anode coated glasssubstrate is also coated with a polymeric ion conductor film using astencil printing or screen printing process. This polymer film may alsorequire a thermal or vacuum drying step or a thermal or UV curing steppost coating.

The anode substrate and cathode substrate are then laminated together ina vacuum lamination process where the substrates are laminated at anelevated temperature, e.g. about 90° C. to about 180° C., and underpressure, typically about 10 psi to about 25 psi.

After lamination, individual devices are cut from the glass using thelaser filamentation processes described herein with laser parametersoptimized for cutting heat strengthened or tempered glass. In oneapproach, each substrate forming the laminate is can from each sideallowing the two substrates to be cut at the same location or differentlocations in the plane. By focusing the laser at a point inside thelaminate near the third surface the laser encounters it is possible tocut just the second glass substrate. By creating two parallel and offsetcuts in each piece of glass it is possible to create an edge thatexposes the inner surface of one of the substrates. This is useful forexposing the TCO film at the edge of one substrate for bus barattachment and electrical contact. It is also possible to generate sucha stepped edge by creating one cut through both pieces of glass and aparallel and offset in the direction of the resultant device. Thisapproach has the advantage that both cuts can be produces from laserenergy being applied from one side of the mother glass.

Example 4

In this example a chemically-strengthened glass substrate is cut with asmooth edge using a laser filamentation process. First, a borosilicateglass, soda lime glass, or aluminosilicate glass substrate is chemicallytoughened to reach a surface stress of around 400 to 800 MPa. Thechemically-strengthened glass substrate is then coated with a lowtemperature, e.g. less than 250° C. TCO film. A low temperature is usedto preserve the chemical-strengthening of the substrate. A proprietaryelectrochromic coating can then be formed on the glass substrate. Theglass substrate is then calcined at a temperature of around 300° C. foraround 1 hour. The glass substrate is then assembled into a device witha glass substrate pair using a polymer ion conductor. The device is thencut down into smaller devices using a laser filamentation process. The“low” temperature process flow and the use of the laser filamentationprocess can result in cutting the chemically-strengthened glasssubstrate without producing cracks and defects around the cut. Anelectrochromic device with improved edge and strength is produced.

Example 5

A set of 15 pieces of heat-strengthened, soda-lime glass, 3.2 mm thick,and having an average surface stress of 40 MPa, was tested using anInstron 3366 equipped with a four point bending fixture, according tothe testing specification described in ASTM C1048. The test data was fitto a Weibull distribution. The characteristic strength, and Weibullmodulus are 145 MPa and 20, respectively. All samples had a modulus ofrupture greater than 100 MPa. The modulus of rupture distribution fit bya Weibull distribution of the results of the foregoing tests are shownon table 2000 of FIG. 20.

Example 6

A set of 15 pieces of heat-strengthened, soda-lime glass, 3.2 mm thick,and having an average surface stress of 85 MPa, was tested using anInstron 3366 equipped with a four point bending fixture, according tothe testing specification described in ASTM C1048. The test data was fitto a Weibull distribution. The characteristic strength, and Weibullmodulus are 164.6 MPa and 16.8, respectively. All samples had a modulusof rupture greater than 100 MPa.

The modulus of rupture distribution fit by a Weibull distribution of theresults of the foregoing tests are shown on table 2100 of FIG. 21.

Example 7

As illustrated by table 2200 of FIG. 22, laser cut annealed SLG isstronger than mechanically cut annealed glass. Laser cut, 85 MPa surfacestress glass is comparable in strength to the 110 MPa mechanicallypre-cut (before tempering) samples.

The foregoing detailed description of the technology herein has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the technology to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. The described embodiments were chosen in order tobest explain the principles of the technology and its practicalapplication to thereby enable others skilled in the art to best utilizethe technology in various embodiments and with various modifications asare suited to the particular use contemplated. The present inventiondescriptions are intended to cover such alternatives, modifications, andequivalents as may be included within the spirit and scope of theinvention as defined by the appended claims and otherwise appreciated byone of ordinary skill in the art.

What is claimed is:
 1. A piece of cut thermally-strengthened glasscomprising: a thermally-strengthened glass substrate having a firstsurface, an opposing second surface, and a peripheral edge between thefirst surface and the second surface, the edge having indicia of a laserfilamentation cutting process, wherein the indicia of a laserfilamentation cutting process comprises a filamentation pattern definedby a series of regularly recurring substantially parallel filamentationtraces.
 2. The cut glass of claim 1, wherein the peripheral edge of thestrengthened glass has a modulus of rupture of greater than about 100MPa and wherein the peripheral edge of the strengthened glass has aprobability of failure of less than about 5% under a 40 MPa load and aWeibull modulus greater than
 10. 3. The cut glass of claim 1, furthercomprising a coating on the peripheral edge of the strengthened glasscomprising metal, oxide material, or a polymer layer.
 4. The cut glassof claim 1, wherein each of such filamentation traces extends from thefirst surface toward the second surface to a depth of at least 75% ofthe thickness as detected by optical microscopy.
 5. The cut glass ofclaim 4, wherein each of such filamentation traces extends from thefirst surface toward the second surface to a depth of at least 90% ofthe thickness as detected by optical microscopy.
 6. The cut glass ofclaim 1, wherein each member of a plurality of the filamentation traceshas a width ranging from about 0.5 microns to about 10 microns.
 7. Thecut glass of claim 1, wherein each member of a plurality of thefilamentation traces has a width ranging from about 1 micron to about 3microns.
 8. The cut glass of claim 1, wherein a set of adjacentfilamentation traces are separated by an average distance ranging fromabout 1 micron to about 30 microns.
 9. The cut glass of claim 1, whereinthe filamentation pattern includes a plurality of filamentation tracesdetectable by optical microscopy wherein each member of the plurality offilamentation traces comprises a filamentation length and afilamentation width and an aspect ratio of greater than about 10:1 asdefined by the ratio of the filamentation length to the filamentationwidth.
 10. An electrochromic composite comprising: a strengthened glasssubstrate having a first surface, an opposing second surface, and aperipheral edge between the first surface and second surface, the edgehaving indicia of a laser filamentation cutting process; an electricallyconductive layer supported on the first surface of the strengthenedglass substrate; and an electrochromic layer in electronic communicationwith the electrically conductive layer.
 11. An electrochromic devicecomprising at least one strengthened glass substrate having a firstsurface, an opposing second surface and a peripheral edge between thefirst surface and second surface, the peripheral edge having indicia ofa laser filamentation cutting process, wherein the indicia of a laserfilamentation cutting process comprises a filamentation pattern definedby a series of regularly recurring substantially parallel filamentationtraces.
 12. The electrochromic device of claim 11, wherein theperipheral edge of the strengthened glass has a modulus of rupture ofgreater than about 100 MPa and a probability of failure of less thanabout 5% under a 40 MPa load.
 13. The electrochromic device of claim 11,further comprising a coating on the peripheral edge of the strengthenedglass comprising metal, oxide material, or a polymer layer.
 14. Theelectrochromic device of claim 11, wherein the indicia of a laserfilamentation cutting process comprises an edge surface having anaverage surface roughness of not more than 5 microns root mean square.15. The electrochromic device of claim 11, wherein each of suchfilamentation traces extends from the first surface toward the secondsurface to a depth of at least 75% of the thickness as detected byoptical microscopy.
 16. The electrochromic device of claim 15, whereineach of such filamentation traces extends from the first surface towardthe second surface to a depth of at least 90% of the thickness asdetected by optical microscopy.
 17. The electrochromic device of claim11, wherein each member of a plurality of the filamentation traces has awidth ranging from about 0.5 microns to about 10 microns.
 18. Theelectrochromic device of claim 11, wherein each member of a plurality ofthe filamentation traces has a width ranging from about 1 micron toabout 3 microns.
 19. The electrochromic device of claim 11, wherein thefilamentation laser traces are separated by an average distance rangingfrom about 1 micron to about 30 microns.
 20. The electrochromic deviceof claim 11, wherein the filamentation pattern includes a plurality offilamentation traces detectable by optical microscopy wherein eachmember of the plurality of filamentation traces comprises afilamentation length and a filamentation width and an aspect ratio ofgreater than about 10:1 as defined by the ratio of the filamentationlength to the filamentation width.
 21. An insulated glass unitcomprising: a first lite comprising a strengthened glass substratehaving a first surface, an opposing second surface and a firstperipheral edge between the first surface and second surface, a secondlite comprising a glass substrate having a first surface, an opposingsecond surface, and a second peripheral edge between the first surfaceand second surface, a spacer element providing spatial separationbetween the first glass lite and the second glass lite, at least one offirst peripheral edge or the second peripheral edge having indicia of alaser filamentation cutting process, wherein the indicia of a laserfilamentation cutting process comprises a filamentation pattern definedby a series of regularly recurring substantially parallel filamentationtraces.
 22. The insulated glass unit of claim 21, wherein the peripheraledge of the strengthened glass has a modulus of rupture of greater thanabout 100 MPa, a probability of failure of less than about 5% under a 40MPa load, and a Weibull modulus greater than
 10. 23. The insulated glassunit of claim 21, wherein one of the layers is an electrochromic layer.24. The insulated glass unit of claim 21, further comprising a coatingon the peripheral edge of the strengthened glass comprising metal, oxidematerial, or a polymer layer.
 25. The insulated glass unit of claim 21,wherein the indicia of a laser filamentation cutting process comprisesan edge surface having an average surface roughness of not more than 5microns root mean square.
 26. The insulated glass unit of claim 21,wherein each of such filamentation traces extends from the first surfacetoward the second surface to a depth of at least 75% of the thickness asdetected by optical microscopy.
 27. The insulated glass unit of claim26, wherein each of such filamentation traces extends from the firstsurface toward the second surface to a depth of at least 90% of thethickness as detected by optical microscopy.
 28. The insulated glassunit of claim 21, wherein each member of a plurality of thefilamentation traces has a width ranging from about 0.5 microns to about10 microns.
 29. The insulated glass unit of claim 21, wherein eachmember of a plurality of the filamentation traces has a width rangingfrom about 1 micron to about 3 microns.
 30. The insulated glass unit ofclaim 21, wherein the filamentation laser traces are separated by anaverage distance ranging from about 1 micron to about 30 microns. 31.The insulated glass unit of claim 21, wherein the filamentation patternincludes a plurality of filamentation traces detectable by opticalmicroscopy wherein each member of the plurality of filamentation tracescomprises a filamentation length and a filamentation width and an aspectratio of greater than about 10:1 as defined by the ratio of thefilamentation length to the filamentation width.